Study On Fractionated Guidance Method Of Non-cooperative Space Rendezvous

With the fast development of space technology,the security problems of spacecraft have received considerable attention.In recent decades,homing guidance technology for non-cooperative spacecraft has been widely used in the space environment exploration,satellite on-orbit servicing,space debris removal and space military confrontation.However,due to the constraints of quality,cost and detector performance,single flight vehicle is difficult to meet both the requirements of detection and interception of non-cooperative spacecraft,which are imposed by the increasingly complex guidance missions.In view of this,this thesis proposes a novel guidance mode — fractionated guidance,which is motivated by the idea of functions assignment of fractionated spacecraft.Compared with the traditional guidance method,the fractionated guidance has the merits of improving the detection and interception performance of non-cooperative target spacecraft,Whereas the characteristics of functions assignment and flight vehicle separation also pose new challenges to the detection and interception methods for non-cooperative target spacecraft.Therefore,focusing on the key issues of detectors configuration,separation condition design and guidance law design under the fractionated guidance scenario,this thesis carries out some in-depth researches on the following aspects.Firstly,the fractionated guidance process for non-cooperative target spacecraft is described.Thereafter,the relative motion models of separation process and interception process are established on the basis of kinematics analysis,which lays a foundation for the research of fractionated guidance.Secondly,the indirect calculation equations of target motion information are derived,and several feasible detection modes for non-cooperative guidance missions are discussed.Furthermore,the calculation error sensitivity and reachable detection geometry of the fractionated guidance are analyzed quantitatively.According to the analysis results,a detecting accuracy analysis method is proposed,and the detection performances with different detection modes are compared and analyzed.Thirdly,the optimization design problem of the separation condition is described.The constraints of separation conditions are analyzed with the consideration of interception ability,interception velocity and the detection time.The optimization index of separation conditions are presented based on the finite time norm.Considering the separationdeviation problem in the practical separation process,a robust optimization algorithms is proposed;Furthermore,to solve the guidance problem with terminal states and control input constraints,a separation point guidance method is proposed based on phase plane planning.Fourthly,based on partitioning Fisher information matrix,the Cramer-Rao low bound of target motion information of the assistant detection mode and binocular detection mode are derived,respectively.The relationship between detection geometry and detection performance of target motion information is discussed quantitatively.Then,the guidance law design problem of fractionated guidance is described,and a predictive guidance law based on optimizing Cramer-Rao low bound is proposed.Finally,aiming at the rendezvous mission for a certain type of non-cooperative target spacecraft,the terminal rendezvous velocity is quantitatively analyzed based on orbital kinematics analysis;furthermore,the separation condition parameters based on the assistant detection mode and binocular detection mode are optimized,respectively;Through guidance simulation,the detection and guidance performance of different detection modes are compared and analyzed,which shows the feasibility and effectiveness of the proposed guidance method.